How To Test Your Back-up Lights and Switch Insitu…..

[boyt911sc]

If your back-lights are not working when you put your transmission to reverse, there are several reasons that could cause this problem, namely:

• A defective back-up switch.
• The light bulbs are busted.
• A wiring harness anomaly.
• The transmission push pin out of position.
• Others.

To deal with this problem, you need to test terminals #5 and #6 for the T14 wire connector located in the engine bay. At the left side of the engine bay is where the fuse panel is located under a plastic protective cover. Remove the black plastic cover and you will find the 14-pin connector.

If you have not separated a 14-pin (male/female) connector before, be aware that the 40-year plus old plastic material would be brittle and could break easily unless you have a new one. So handle this job cautiously with tender loving care. And take some pictures just in case something happens unexpectedly.

First step is to get access to the 14-pin connector in the engine bay.
Picture #1:


Picture #2: The 14-pin connector is now accessible.


Picture #3:
With ignition switch @ OFF position, only pin #14 has power. Terminal #14 is HOT all the time unless you disable the battery. But we need power to do the test. I was using an awl or an ice pick to separate the female plug from the male plug (T14 connector).



Picture #4:
The #5 and #6 pins are shown below. If you zoom the picture below, the pins are individually numbered. Odd numbers (1~13) bottom row and even numbers (2~14) top row.


Picture #5:
When ignition switch is OFF, pin #5 has NO POWER. When you switch the ignition switch to ON position (not start) pin #5 is energized (power is present). So bridging pin #5 and #6 is same as bridging the back-up switch terminals. And the back-up lights lit up with the transmission in NEUTRAL. TEST RESULT: Wiring and light bulbs confirmed good and working.


Please note I was using a motor with 915 transmission for this demonstration and tested the back-up lights and switch with ignition switch ON. Both lights and reverse switch confirmed good and working.

Before using the jumper wire, I had the ignition @ ON, gear in NEUTRAL, back-up lights OFF, and finally bridged #5 and #6…………….both back-up lights (diver side and passer side) LIT UP! Remember that the gear is in NEUTRAL. So what have we achieved? We have demonstrated that the wiring and the back-up lights are good and working without using the back-up switch.

Unfortunately, I don’t have any defective BACK-UP SWITCH to test. Next project is to test a defective back-up switch and transmission push pin.

Tony